LXR linux/sound/soc/codecs/adau-utils.c

   1/*
   2 * Shared helper functions for devices from the ADAU family
   3 *
   4 * Copyright 2011-2016 Analog Devices Inc.
   5 * Author: Lars-Peter Clausen <lars@metafoo.de>
   6 *
   7 * Licensed under the GPL-2 or later.
   8 */
   9
  10#include <linux/gcd.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13
  14#include "adau-utils.h"
  15
  16int adau_calc_pll_cfg(unsigned int freq_in, unsigned int freq_out,
  17        uint8_t regs[5])
  18{
  19        unsigned int r, n, m, i, j;
  20        unsigned int div;
  21
  22        if (!freq_out) {
  23                r = 0;
  24                n = 0;
  25                m = 0;
  26                div = 0;
  27        } else {
  28                if (freq_out % freq_in != 0) {
  29                        div = DIV_ROUND_UP(freq_in, 13500000);
  30                        freq_in /= div;
  31                        r = freq_out / freq_in;
  32                        i = freq_out % freq_in;
  33                        j = gcd(i, freq_in);
  34                        n = i / j;
  35                        m = freq_in / j;
  36                        div--;
  37                } else {
  38                        r = freq_out / freq_in;
  39                        n = 0;
  40                        m = 0;
  41                        div = 0;
  42                }
  43                if (n > 0xffff || m > 0xffff || div > 3 || r > 8 || r < 2)
  44                        return -EINVAL;
  45        }
  46
  47        regs[0] = m >> 8;
  48        regs[1] = m & 0xff;
  49        regs[2] = n >> 8;
  50        regs[3] = n & 0xff;
  51        regs[4] = (r << 3) | (div << 1);
  52        if (m != 0)
  53                regs[4] |= 1; /* Fractional mode */
  54
  55        return 0;
  56}
  57EXPORT_SYMBOL_GPL(adau_calc_pll_cfg);
  58
  59MODULE_DESCRIPTION("ASoC ADAU audio CODECs shared helper functions");
  60MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
  61MODULE_LICENSE("GPL v2");
  62